Integrated circuits, in particular those equipped with memories containing sensitive information, must, as much as possible, be protected from attacks, in particular attacks intended to discover the data stored in memory.
One possible type of attack may be carried out from the back side of an integrated circuit, using a laser beam.
The effectiveness of such an attack increases when the substrate of the integrated circuit is thinned by the attacker from its back side so as minimize the distance through the substrate to the components of the integrated circuit produced on its front side. The integrated circuit may, for example, be thinned from the back side using a focused ion beam (FIB) and/or using a polishing/grinding step.
Means allowing thinning of the substrate from its back side to be detected do exist. This being so, these means sometimes have a low degree of integration, and may sometimes disrupt operation of components located nearby.
These existing means may, for example, detect a variation in resistance with the thinning of the substrate. This being so, this type of solution may be a source of errors, in particular in integrated circuits where the temperature is allowed to vary which results in a variation in resistance value even in the absence of thinning.